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-   -   Strange loss of braking ability. What happened? (https://www.team-bhp.com/forum/technical-stuff/149153-strange-loss-braking-ability-what-happened-2.html)

Cadence braking works wonders here.
I have been saved numerous times by that + defensive driving.

Please don't ignore this by not getting it checked, do update us on Saturday.

Loss of steering control along with braking control also happens when there is a problem in the electrical circuit or the electronics - perhaps the engine died for some time?

For once, on a down slope, switch off the ignition and try to brake and/or steer. If the feeling is same I think you have caught the culprit!
However be ready with the handbrake :) you don't want to cause an accident.

You mean could the engine have stalled as the engine was ON and the transmission engaged causing the car to stall loosing out on steering and braking power?

Anurag.

But in these cases of engine stalling and while rolling down the slope, if your car is in a gear, it will keep the engine running; though only mechanically, even with ignition off, and the engine will keep on creating the negative pressure or the vacuum needed for braking. The loss of braking will only be there if the car was rolling in neutral.

This has happened a couple of times to me as well - i got all brakes checked and even changed the brake pads (which were not due for replacement) just for my piece of mind. It did NOT help. Honda City brakes are completely BOGUS!

The only thing that helps is dont let the brake pads heat up - take your foot off from braking for a split sec. Maybe a couple times as well and surely you will stop!

I too have a weird problem with braking on Spark car.

The issue is that suppose i am in a gear (lets say 2nd), and then without downshifting or shifting to neutral, i brake. All is well. Now i release brake pedal and let the car continue without giving accelerator input, and again brake 2-3 times, then after the 3rd or 4th attempt - the braking has no effect. As if the engine is shut off and it keeps moving in the momemtum without stopping. Sometimes it gets scary in stop and go traffic, where i don't use accelerater but continue braking 2-3 times in same gear without operating the accelerator.

Anyone faced similar issue?

Agreed, I was thinking about neutral gear / clutch engaged scenario.
Some people do press clutch while braking.
Agreed. But do consider that some people press brake and clutch together. So engine killed can be the culprit.

If not then this looks like a case of oil slick. I faced this a few weeks back traveling uphill from Bombay to Pune on expressway. Some idiot vegetable oil tanker had pooped all over the road.


However I would still place my bet on some electrical problem.
The brake assist and the steering assist were affected which run on electricity

I had faced a similar incident, I had to brake / slow down to let a cow cross the road. Pressed the brake, the car just moved ahead as if i've not applied the brake, I had to press it really hard and it stopped further than than i intended, somehow avoided the cow. After that the brakes were fine throughout.

The problem is due to the brake booster not being able to maintain the vacuum. Typical service life of a brake booster is about 70,000 to 80,000 KM, after which it has to be replaced as per the service schedule. The booster diaphragm gets worn out/stiff over time and it can get unreliable in maintaining the vacuum. Without the vacuum, the booster assisted brake system is simply ineffective and will require far greater foot pressure.
In my case i decided to replace the brake booster promptly at 70K Km as a preventive maintenance. Brakes not working is a very scary situation to be in and is likely to re-occur anytime, especially if you stomp on the brakes suddenly.
If you ever encounter the situation again. let go off the brakes and apply it again and pray.

Better get your brake booster replaced for peace of mind and in the interest of safety. There can be no compromise made here. The booster is a critical part and it has to work flawlessly at all times.

Are you pressing the brakes in super rapid succession like 3 to 4 times continuously in a row? Like, Press, release, Press release, press release, press release. Like you know BANG BANG BANG BANG. If so, you are not allowing the vacuum to fill the booster for it to start working again. Happens to every car. You can try it on your friends car too if you want. Go militant with the applying and releasing of the brake pedal and even a completely working broke booster will not fill in vacuum that quick and the brakes will harden up.

Check your brake booster like I have mentioned below and post the result.

To check if the brake booster is leaking or no, perform this simple test.

Stop the car in the night like how you normally do. In the morning, press the brakes, if the brake booster is leaking, the pedal will be rock hard, if the brake booster is not leaking vacuum, the first 2 attempts or so will be soft after which the pedal will harden up again.

Frankly speaking, I have not encountered this problem anytime in my car. Although, pumping brakes for slowing down from high speed apart from engine braking is a good technique, but I have never felt loss of braking efficiency while constantly holding down the brakes for slowing down. May be holding down the brakes slowly for loooong time will result in efficiency loss until the pads cool down.

Agreed with your booster testing procedure. One can also hear air being sucked in while pressing the brake pedal in during such test.

PS: from OP's experience, I feel that he might have had a locked up wheel situation. He may not have noticed the sound of the skid due to rolled up windows + AC+ stereo or other reasons, but since he saw skid marks, I think it was a wheel lock up situation.

Doesn't it happen fast, I mean within seconds of the brake release?

I agree on the brake booster leak but on a normal car the refill should happen fast as I have never faced such an issue in any of my cars till date though I do that 'BANG BANG BANG' thing (Not frequently though)!

Anurag.

I had faced similar situation multiple times in my 2000 Santro since it was new. There was no diagnosis made by service center and finally on my request and payment they replaced vacuum booster or brake booster. And problem was solved. Your problem is similar to mine and I too have a Honda City, I haven ever experienced brake getting hot that they leave friction even after extensive aggresive driving

Pumping brakes for slowing down is a good practice, but the scenario is different when you pump the brakes at super sonic speeds, that time the booster won't cope up and u ll see the brake pedal harden. Try it out when you are in the parking lot. Pump it super fast a couple of times and see it get hard.

Also the scenario about the brakes getting hot changes depends on the weight of the car, speed at which its moving while the brakes were continuously pressed, weather conditions etc etc.

I have braked hard many times, many a times I have faced exactly what the OP did and many a times if it has been a cool day, the brakes have not overheated and there has been no brake fade at all. Although I consciously try and remember to let them off for a second during a hard braking, but sometimes consciously/unconsciously you just slam them on.

Yes the refilling happens fast, but 'seconds' is a long time, what I meant by bang bang bang bang was at a super rapid rate. Within less than two seconds, you have pushed it and released 3 to 4 times, the next push will be on a hard pedal then.

Try it out in the parking lot and see the pedal get hard if you do it too fast.

:thumbs up

Ok things cleared, just tried the 'BANG' thing now, yes, the brake pedal did get hard when pumped at a very fast rate without much gap in between two pumps.

Anurag.

But your engine must be at idle during this experiment, isn't it?